This invention relates to cleaner/degreaser compositions and, more particularly, to cleaner/degreaser concentrate compositions which are especially adapted to readily and rapidly form the totally water soluble solutions of the compositions of U.S. Pat. No. 5,080,831 when diluted with sufficient water to produce a solution of desired concentration or cleaner/degreaser strength.
In my coassigned U.S. Pat. No. 5,080,831, there are disclosed aqueous cleaner/degreaser compositions in the form of totally water soluble solutions which exhibit superior cleaning and degreasing capability. Such compositions comprise (a) at least one sparingly water soluble organic solvent having certain defined characteristics; (b) a solubilizing additive consisting of from approximately 0.1 to approximately 100 weight percent of a surfactant and from 0 to approximately 99.9 weight percent of a coupler, the solubilizing additive being present in an amount not exceeding approximately twofold that required to completely solubilize the organic solvent; and (c) water.
Since the cleaner/degreaser compositions of my U.S. Pat. No. 5,080,831 generally contain a high proportion of water, it would be advantageous to eliminate the free added water from such compositions and form concentrates which would be more economical and less wasteful to ship and store prior to usage. However, it has been found that when concentrates are formulated by eliminating free added water from the compositions of my ""831 patent, such concentrates upon the addition of the appropriate amount of water to yield the final compositions of my ""831 patent require an undue amount of time and agitation to produce ready to use compositions. Thus, for example, a concentrate containing the theoretical proportions of organic solvent and solubilizing additive components as taught in my ""831 patent with free added water removed may, upon the addition of the requisite amount of water, require 10-15 minutes with stirred mixing before it is converted from the initial turbid, cloudy emulsion state to one of a truly clear, aqueous solution as contemplated for use in cleaning and degreasing by my ""831 patent.
It would be beneficial and advantageous to have available for economical shipping and storage a concentrate composition which does not suffer from such drawbacks and which may be readily transformed, upon the addition of sufficient water, to form clear solutions of desired strength.
Among the several objects of the invention may be noted the provision of substantially nonaqueous concentrates for use in preparing stable, aqueous cleaner/degreaser compositions having superior cleaning/degreasing efficacy; and the provision of such concentrates which upon dilution with water rapidly and readily form aqueous cleaner/degreaser compositions containing the desired level or weight percent of a sparingly water soluble organic solvent; and the provision of such compositions which may be readily formulated from available components. Other objects and features will be in part apparent and in part pointed out hereinafter.
Briefly, the present invention is directed to a substantially nonaqueous concentrate for use in preparing a stable aqueous cleaner/degreaser composition in the form of a totally water soluble composition. The concentrate comprises:
(a) at least one sparingly water soluble organic solvent characterized by:
(i) having a water solubility in the range of approximately 0.2 to approximately 6 weight percent of the totally water soluble solution formed from the concentrate;
(ii) not being a hydrocarbon or halocarbon;
(iii) having oxygen, nitrogen, sulfur or phosphorus containing functional groups;
(iv) being a solvent for hydrophobic soilants and
(v) being present in an amount exceeding its aqueous solubility in the totally water soluble solution formed from the concentrate;
(b) a solubilizing additive consisting of from approximately 0.1 to approximately 100 weight percent of a surfactant and from 0 to approximately 99.9 weight percent of a coupler, the solubilizing additive being present in an amount of approximately 3% to approximately 15% by weight excess over that minimally required to form a clear solution when the concentrate is combined with water; and
(c) not more than 10.0 weight percent of water;
(d) the concentrate forming a barely clear, totally water soluble solution when diluted with sufficient water to produce resulting solutions of desired strength. The concentrates of the invention are thus adapted for economical shipping and storage while permitting the rapid and convenient preparation therefrom of the aqueous cleaner/degreaser compositions of my U.S. Pat. No. 5,080,831.
In accordance with the present invention, it has been found useful concentrates which can be rapidly and readily transformed, upon the addition of sufficient water, to a ready-to-use, clear, totally water soluble solution of the type described in my U.S. Pat. No. 5,080,831 are comprised of at least one sparingly water soluble organic solvent having certain characteristics, a solubilizing additive as described in my ""831 patent and being present in an amount of approximately 3% to 15% by weight excess over that minimally or theoretically required to form a clear solution when the concentrate is combined with water, and not more than 10.0 weight percent of water. While in theory, concentrates may be formed from the stable, aqueous cleaner/degreaser compositions of my ""831 by simply removing or eliminating free added water therefrom, in actual practice it has been found that concentrates so formed when recombined with sufficient water require extended periods of from 5 to 10 minutes or more with stirring to undergo full dissolution from the concentrate to emulsion to the desired clear solution state. This drawback severely limits the practical utility of such theoretical concentrate compositions in the convenient preparation of the ready-to-use cleaner/degreaser compositions of my ""831 patent. Through the present invention, I have found that this drawback may be overcome by formulating concentrates containing an excess of from approximately 3% to approximately 15% by weight of solubilizing additive (surfactant plus optional coupler) over that minimally or theoretically required to form a clear solution when the concentrate is combined with water. Concentrates formulated in accordance with the present invention advantageously, rapidly and readily form a barely clear, totally water soluble solution when diluted with water to produce a solution having the desired strength. The present invention thus provides concentrates which may be economically shipped and stored and in turn be readily and rapidly converted into ready-to-use cleaner/degreaser compositions of my ""831 patent with their attendant superior cleaner/degreaser capability.
It should be noted that a number of surfactants and couplers useful in the present invention are often commercially available or useful only as aqueous solutions, gels or pastes containing some proportion of water. The introduction of water from these sources into the nonaqueous concentrates of the invention constitutes not more than 10.0 weight percent of the concentrate composition and in no instance is water intentionally added as a component of the concentrates of the invention. It should also be noted that the low levels of water introduced into the resultant concentrates from such sources may function as a compatabilizing agent between the organic solvent component, the solubilizing additive and extraneous by product components such as salts, especially sodium chloride. In some instances, where total selectivity of the solubilizing additive is possible, the concentrates of the invention are truly nonaqueous.
For use in the present invention, the sparingly water soluble organic solvent must have the following characteristics:
(a) it must have limited water solubility in the range of approximately 0.2 to 6 weight percent;
(b) it must not be a hydrocarbon or halocarbon;
(c) it must have one or more similar or dissimilar oxygen, nitrogen, sulfur or phosphorous containing functional groups;
(d) it must be a solvent for hydrophobic soilants; and
(e) it must be present in an amount exceeding its limited aqueous solubility.
Organic solvents meeting these criteria provide superior cleaning/degreasing action when formulated in accordance with the invention.
The principal classes of organic solvents from which useful organic solvents may be selected include esters, alchohols, ketones, aldehydes, ethers and nitriles. These will generally contain one or more of the desired similar or dissimilar functional groups listed above. Examples of organic solvents containing similar functional groups from among those listed above include diethyl gluterate (2 ester groups), phenacyl acetone (2 keto groups), diethylethylene diphosphonate (2 phosphonate ester groups), ethylene-dipropionate (2 ester groups), decylene glycol (2 hydroxyl groups), m-dimethoxybenzene (2 ether groups), adiponitrile (2 nitrile groups), ethylene glycol dibutyl ether (2 ether groups), and diethyl-o-phthalate (2 ester groups). Among organic solvents containing dissimilar functional groups from among those listed above may be mentioned 2-phenoxyethanol (hydroxy, ether groups), 1-phenoxy-2-propanol(hydroxy, ether groups), N-phenylmorpholine(amino, ether groups), isopropylacetoacetate (keto, ester groups), o-methoxybenzyl alcohol (ether, hydroxy groups), 4xe2x80x2-methoxyacetophenone (ether, ketone groups), o-nitrophenetole (nitro, ether groups), 2-hexoxyethanol (hydroxy, ether groups), ethylcyanoacetoacetate (cyano, keto, ester groups), p-anisaldehyde (ether, aldehyde groups), polypropylene glycol 1200 (ether, hydroxyl groups), n-butoxy acetate (ether, ester groups), and 2-phenylthioethanol (thioether, hydroxyl groups).
In addition to the criteria listed above, it is also desirable but not essential that the organic solvent have a relatively low volatility or high flash point, exhibit a low level of odor, be chemically stable, nontoxic, nonhazardous and commercially available.
The sparingly water soluble organic solvents which may be employed in the practice of the present invention (and comprising some of the solvents listed above) together with their aqueous ambient temperature solubility in wt. % include 2-phenoxyethanol (2.3) (marketed under the trade designation xe2x80x9cDowanol EPhxe2x80x9d), 1-phenoxy-2-propanol (1.1) (marketed under the trade designation xe2x80x9cDowanol PPhxe2x80x9d), xcex2-phenylethanol (1.6), acetophenone (0.5), benzyl alcohol (4.4), benzonitrile (1.0), n-butyl acetate (0.7), n-amyl acetate (0.25), benzaldehyde (0.3), N,N-diethylaniline (1.4), diethyl adipate (0.43), dimethyl-o-phthalate (0.43), n-amyl alcohol (2.7), N-phenylmorpholine (1.0), n-butoxyethyl acetate (EB acetate) (1.1), cyclohexanol (4.2), polypropylene glycol 1200 (2), cyclohexanone (2.3), isophorone (1.2), methylisobutyl ketone (2.0), methylisoamyl ketone (0.5), tri-n-butylphosphate (0.6), 1-nitropropane (1.4), nitroethane (4.5), dimethyl esters of mixed succinic, glutaric and adipic acids (5.7) (marketed under the trade designation xe2x80x9cDBE esterxe2x80x9d by DuPont), diethyl glutarate (0.88), and diethyl malonate (2.08). As will be apparent to those skilled in the art, the above-listed sparingly water soluble organic solvents are merely illustrative and various other solvents meeting the criteria set out above may also be utilized in the practice of the invention. Because of their performance characteristics, lack of odor, low volatility/high flash point, chemical stability and availability, 2-phenoxyethanol and 1-phenoxy-2-propanol are the preferred organic solvents of choice. N-butoxyethyl acetate (EB acetate) and the dimethyl esters of mixed succinic, glutaric and adipic acids are also among the preferred organic solvents.
As indicated, a number of otherwise potent organic solvents having an aqueous solubility of less than approximately 0.2 weight percent such as 2-(2-ethylhexoxy)-ethanol (2-ethylhexyl cellosolve) having an aqueous solubility of only 0.095 wt. %, and 2,6-dimethyl-4-heptanone(diisobutyl ketone) (aq. sol. 0.05 wt. %), and organic solvents having an aqueous solubility in excess of approximately 6 weight percent such as propylene glycol monomethyl ether acetate (aq. sol. 16.5 wt. %), ethylene glycol diacetate (aq. sol. 14.3 wt. %), propylene carbonate (aq. sol. 19.6 wt. %) and N-methyl pyrrolidone (infinite aq. sol.) are not useful in the practice of the invention.
The solubilizing additive consists of from approximately 0.1 to approximately 100 weight percent of a surfactant and from 0 to approximately 99.9 weight percent of a coupler and the solubilizing additive is preferably present in the formulated composition in an amount not substantially exceeding that required to completely solubilize the particular organic solvent being used, i.e. a minimum level of the solubilizing additive is used in order to render the organic solvent xe2x80x9cbarely solublexe2x80x9d in the aqueous solution so as to achieve maximum or optimum degreasing action. The amount of solubilizing agent (surfactant or surfactant plus coupler) required to accomplish this objective will vary depending upon the particular organic solvent employed and can readily be determined by simple experimentation in each instance.
The solubilizing additive used in the practice of the invention may consist of a surfactant or a surfactant in combination with a coupler. As used herein, the term xe2x80x9ccouplerxe2x80x9d is intended to mean a hydrotrope or a substance that increases the solubility in water of another material which is only partially water soluble, such as organic solvents or surfactants. In some instances, the use of a surfactant alone will suffice to render the organic solvent component of the compositions just completely soluble while in other instances the use of a surfactant in combination with a coupler may be utilized to achieve the desired complete aqueous solubilization of the organic solvent. Whether or not a surfactant alone or the combination of a surfactant and coupler is to be used is dependent upon the particular organic solvent and surfactant employed and can readily be determined in each particular case by simple experimentation.
The surfactant used may be an anionic, nonionic, cationic or amphoteric surfactant, and the use of anionic or nonionic surfactants is generally preferred, especially for hard surface cleaning/degreasing. Illustrative anionic surfactants for use in the invention include dodecylbenzenesulfonic acid, sodium dodecylbenzene sulfonate, potassium dodecylbenzene sulfonate, triethanolamine dodecylbenzene sulfonate, morpholinium dodecylbenzene sulfonate, ammonium dodecylbenzene sulfonate, isopropylamine dodecylbenzene sulfonate, sodium tridecylbenzene sulfonate, sodium dinonylbenzene sulfonate, potassium didodecylbenzene sulfonate, dodecyl diphenyloxide disulfonic acid, sodium dodecyl diphenyloxide disulfonate, isopropylamine decyldiphenyloxide disulfonate, sodium hexadecyloxypoly(ethyleneoxy)(10)ethyl sulfonate, potassium octylphenoxypoly(ethyleneoxy)(9)ethyl sulfonate, sodium alpha C12-14 olefin sulfonate, sodium hexadecane-1 sulfonate, sodium ethyl oleate sulfonate, potassium octadecenylsuccinate, sodium oleate, potassium laurate, triethanolamine myristate, morpholinium tallate, potassium tallate, sodium lauryl sulfate, diethanolamine lauryl sulfate, sodium laureth (3) sulfate, ammonium laureth (2) sulfate, sodium nonylphenoxypoly(ethyleneoxy)(4) sulfate, sodium diisobutylsulfosuccinate, disodium laurylsulfosuccinate, tetrasodium N-laurylsulfosuccinimate, sodium decyloxypoly(ethyleneoxy(5)methyl)carboxylate, sodium octylphenoxypoly(ethyleneoxy(8)methyl)carboxylate, sodium mono decyloxypoly(ethyleneoxy)(4)phosphate, sodium didecyloxypoly(ethyleneoxy)(6)phosphate, and potassium mono/di octylphenoxypoly(ethyleneoxy)(9)phosphate. Other anionic surfactants known in the art may also be employed.
Among the useful nonionic surfactants which may be employed may be mentioned octylphenoxypoly(ethyleneoxy)-(11)ethanol, nonylphenoxypoly(ethyleneoxy)(13)ethanol, dodecylphenoxypoly(ethyleneoxy)(10)ethanol, polyoxyethylene (12) lauryl alcohol, polyoxyethylene (14) tridecyl alcohol, lauryloxypoly(ethyleneoxy)(10)ethyl methyl ether, undecylthiopoly(ethyleneoxy)(12)ethanol, methoxypoly(oxyethylene-(10)/(oxypropylene(20))-2-propanol block copolymer, nonyloxypoly(propyleneoxy)(4)/(ethyleneoxy)(16)ethanol, dodecyl polyglycoside, polyoxyethylene (9) monolaurate, polyoxyethylene (8) monoundecanoate, polyoxyethylene (20) sorbitan monostearate, polyoxyethylene (18) sorbitol monotallate, sucrose monolaurate, lauryldimethylamine oxide, myristyldimethylamine oxide, lauramidopropyl-N,N-dimethylamine oxide, 1:1 lauric diethanolamide, 1:1 coconut diethanolamide, 1:1 mixed fatty acid diethanolamide, polyoxyethylene(6)lauramide, 1:1 soya diethanolamidopoly(ethyleneoxy)(8) ethanol, coconut diethanolamide, xe2x80x9cmodifiedxe2x80x9d, and coconut diethanolamide, xe2x80x9clong chain modifiedxe2x80x9d. Other known nonionic surfactants may likewise be used.
Illustrative useful cationic surfactants include a mixture of n-alkyl (C12 50%, C14 30%, C16 17%, C18 3%) dimethyl ethylbenzyl ammonium chlorides, hexadecyltrimethylammonium methosulfate, didecyldimethylammonium bromide and a mixture of n-alkyl (68% C12, 32% C14) dimethyl benzyl ammonium chlorides. Similarly useful amphoteric surfactants include cocamidopropyl betaine, sodium palmityloamphopropionate, N-coco beta-aminopropionic acid, disodium N-lauryliminodipropionate, sodium coco imidazoline amphoglycinate and coco betaine. Other cationic and amphoteric surfactants known to the art may also be utilized.
The preferred surfactants for general use in the practice of the invention include dodecylbenzenesulfonic acid and the sodium, potassium, triethanolamine, morpholinium, ammonium and isopropylamine salts thereof, and morpholinium tallate.
The couplers which may be utilized in the practice of the invention include sodium benzene sulfonate, sodium toluene sulfonate, sodium xylene sulfonate, potassium ethylbenzene sulfonate, sodium cumene sulfonate, sodium octane-1-sulfonate, potassium dimethylnaphthalene sulfonate, ammonium xylene sulfonate, sodium n-hexyl diphenyoxide disulfonate, sodium 2-ethylhexyl sulfate, ammonium n-butoxyethyl sulfate, sodium 2-ethylhexanoate, sodium pelargonate, sodium n-butoxymethyl carboxylate, potassium mono/di phenoxyethyl phosphate, sodium mono/di n-butoxyethyl phosphate, triethanolamine trimethylolpropane phosphate, sodium capryloamphopropionate, disodium capryloiminodipropionate, and sodium capro imidazoline amphoglycinate. Certain water-soluble solvents known to the art as couplers such as propylene glycol ethers (e.g. tripropyleneglycol-monomethyl ether) can be used in the practice of the invention, but cannot be substituted for the sparingly water soluble organic solvent component. Additional couplers or hydrotropes known to the art may also be utilized.
In regard to the solubilizing additive component of the compositions of the invention, it will be understood that one or more surfactants from one or more compatible classes of surfactants may be employed or utilized in a mixed solubilizing surfactant system. For example, a combination of compatible anionic and nonionic surfactants may be employed. Likewise, a combination of compatible couplers may also be used as may a combination of one or more compatible surfactants from different classes of surfactants together with one or more couplers. Thus, one may use a combination of blended surfactants and couplers to achieve the desired minimal solvent solubilization. The compatibility of the various surfactants and of the various couplers with each other and in combination can be readily determined by simple experimentation.
Similarly, but less preferably, a mixture of the sparingly soluble organic solvents may be employed in formulating the compositions of the invention. However, if a mixture of solvents is to be used, each of the solvents should have nearly the same approximate water solubility so that they will solubilize in water at approximately the same point upon addition of the solubilizing additive.
In addition to the organic solvent and solubilizing additive components of the compositions of the invention, various optional adjuvants can be incorporated. These include chelants such as the sodium salts of ethylene-diaminetetraacetic acid (Hampene 100 or Versene 100), thickeners such as carboxy acrylic polymers (Carbopol 940) or acrylic acid/alkyl methacrylate copolymers (Acrysol ICS-1), fragrances, dyes, pH adjustants, anti-corrosion additives and anti-rust additives.
In preparing the concentrates of the invention, the required proportions of organic solvent and solubilizing additive may simply be combined with each other, with the solubilizing additive being present in an amount of approximately 3% to approximately 15% by weight excess over that minimally or theoretically required to rapidly and readily form a clear solution when the concentrate is combine with water. In any particular combination of organic solvent and solubilizing additive within the scope of the present invention, the excess of solubilizing additive required may be readily determined by trial and error experimentation.
In the following examples which illustrate the practice of the invention, all experiments were run at ambient temperature conditions, i.e. at 21xc2x11xc2x0 C. (ca 68-72xc2x0 F.). These examples illustrate that the incorporation of excess solubilizing additive into the concentrates of the invention speeds or accelerates the transformation of dispersion of the concentrate to the clear solution state under normal mixing condition or conditions applied under normal use conditions. By performing the experiments at ambient temperatures, problems associated with cloud points of water diluted compositions and solution clarity are obviated. Some solubilizing additives and sparingly water soluble organic solvents exhibit this cloud point phenomenon in water to some degree and generally the cloud point of such a system is inversely proportional to its temperature. If higher use temparature conditions are to be employed, then higher levels of solubilizing additive must also be employed to compensate for the reduced aqueous solubilities of the sparingly water soluble organic solvents at elevated temperatures.
The following examples illustrate the principles of the invention. For comparison purposes, each cleaner/degreaser concentrate shown in these examples is diluted with sufficient water to form diluates containing not more than 6 weight percent of the organic solvent component, 6 weight percent being the aqueous solubility limit for the most soluble of the sparingly water soluble organic solvents useful in the practice of the invention as indicated above. By definition, in each instance, the diluates must be and are barely clear aqueous solutions. It will be understood that in accordance with the invention, the concentrates may be diluted to any desired strength/solvent concentration depending upon the desired use of the resulting aqueous cleaner/degreaser compositions.
The following examples illustrate the practice of the invention.